Energy absorbing system



v. c. J. lFETERSQN ENERGY ABsoRBING SYSTEM lMarch 4, 1969 Y. t////A.7////////J7////////// m WM.- P w l H Il!.7///////////v//////////yW/////Qr 4 \m L Il mi .yh Il. a www@ Q 2 m. M st March 4, 1969 v. c. J. PETERSON 3,430,897

ENERGY ABSORBING SYSTEM Original Filed Deo. 23, 1965 Sheet of 5 O IO 2030 40 '50 60 70 8O 90 |00 IIO I2C |30 Percent E longoTion e INVENTORVincent C.J. Peterson ATTO NEYS March 4, 1969 v. c. J. PETERSON3,430,897

ENERGY ABSORBING SYSTEM Uriginal Filed Dec. 23, 1965 Sheet i of I3 FIG.5

INVENTOR Vincent C. J. Peterson ORNEYS United States Patent O 3,430,897ENERGY ABSORBING SYSTEM Vincent C. J. Peterson, Huntingdon Valley, Pa.,assignor to American Chain t Cable Company, Inc., New York, N.Y., acorporation of New York Original application Dec. Z3, 1965, Ser. No.515,979, new Patent N o. 3,353,768, dated Nov. 21, 1967. Divided andthis application July 24, 1967, Ser. No. 671,513 U.S. Cl. 244-110 1Claim Int. Cl. B64c 25/68, 25/58 ABSTRACT F THE DISCLOSURE A kineticenergy absorbing device connecting a load receiving pendant with ananchorage point, the device comprising a plurality of cables arranged inparallel with slack being present in the respective cables in varyingamounts in the initial position of the load receiving means so that thecables are placed under tension sequentially during application of theload.

This invention relates to devices for absorbing kinetic energy, and moreparticularly to a device which includes extensible cables for absorbingincreasing amounts of energy in stages. This application is a divisionof Ser. No. 515,979, filed Dec. 23, 1965.

Though this new energy absorbing device has a Wide variety of uses, itis particularly well suited to aircraft arresting equipment. In orderthat an energy absorbing system be capable of arresting aircraft of awide range of weight and speed, it is necessary that a system designedto arrest the faster and heavier aircraft shall not offer too muchresistance to the lighter aircraft. Otherwise, the great resistanceencountered may result in too rapid deceleration of the aircraft, whichis unsafe for passengers, or in extreme cases the breaking or pullingoff of the aircraft arresting hook. Certain energy absorbing systems inthe past have attempted to meet these demands by offering varyingresistance to the vehicle in motion as that vehicle is being arrested,but invariably these systems utilize cornplicated independent means forabsorbing energy in a sequential manner. It is the purpose of thisinvention to provide arresting means wherein a simple system ofextensible cables is used to absorb energy sequentially, therebyreducing greatly the degree of complication of the apparatus andinsuring that it can satisfactorily arrest the motion of objects ofwidely varying mass.

Broadly stated, the invention provides an improved energy absorbingdevice interconnecting anchorage means and load receiving meansdisplaceable from an initial position with respect thereto in apparatusfor absorbing kinetic energy. Two or more extensible cables are cojoinedwith one another and the load receiving and anchorage means and they areadapted to be elongated during application of the load and displacementof the load receiving means. Sequentially operable means are providedfor controlling the relative elongation of the cables so thatincreasingly more load is required to displace the load receiving meansfrom its initial position through subsequent positions corresponding innumber to t-he number of the cables.

In one general form of the invention, the cables are adapted to beplaced simultaneously in tension upon application of the load and arecapable of differing amounts of elongation under a given tensile force.The sequentially operable means in that case comprises stop means which3,430,897 Patented Mar. 4, 1969 ICC prevents the more easily extensiblecable or cables from elongating beyond the breaking point `withoutinterfering with the elongation of the less easily extensible cable orcables. In another form of the invention the cables are arranged inparallel between the load receiving and anchorage means, thesequentially opera'ble means being slack which is present in therespective cables in varying amounts in the initial position of the loadreceiving means so that the cables are placed in tension sequentiallyduring application of the load and displacement of the load recervmgmeans.

By arranging various cables in this fashion, aircraft or other objectsof varying size and weight can be arrested without exceeding criticallimits of deceleration. The components of the new system possess amarked degree of simplicity of both with respect to their constructionand operation so that capital and maintenance costs can be kept to aminimum. These and other advantages of the invention will -be apparentfrom the following detailed description of preferred embodiments,wherein:

FIG. 1 is a schematic plan view of one embodiment of the new arrestingdevice employed as an aircraft arresting device;

FIG. 2 is a similar view of a relatively light plane being arrested bythat arresting device;

FIG. 3 is a similar view of a relatively heavy plane being arrested bythat arresting device;

FIG. 4 is a similar view of -another embodiment of the invention;

FIG. 5 is a similar view of a third embodiment of the invention; and

FIG. 6 is a stress-strain curve characteristic of a particularembodiment of the invention.

In FIG. 1, a pendant 10 extends in its initial position across a runway11 on which an aircraft is to be arrested. The pendant 10 or loadreceiving means is adapted to be picked up by and secured to theaircraft to be arrested. A pair of anchorage blocks 12 are placed oneach side of the runway 11 and are spaced from the pendant 10 in thedirection from which the aircraft approaches the pendant 10. A series ofannealed stranded wire extensible cables 13, 14, and 16 joined end toend interconnects each anchorage block 12 with one end of the pendant10. Each series of cables 13, 14, 15 and 16 extends substantiallylinearly along its respective side of the runway 11 and the two seriesare parallel to one another. The cables 13, 14, 15 and 16 are splicedend-to-end by ttings 17, 18 and 19. Each cable 13, 14, 15 and 16 iscapable of elongating under load, but the physical properties of thecables 13, 14, 15 and 16 are such that cable 14 elongates to a lesserextent under a given tensile force than the cable 13, the cable 15elongates to a lesser extent under a given tensile force than the cable14, and the cable 16 elongates to a lesser extent under a given tensileforce than the cable 15. This may 'be done, for example, by using thesame material for each cable, but with each cable having a diameter lessthan its neighboring cable secured closer to the pendant 10.

Thus, when the series of cables 13, 14, 15 and 16 is placed under a loadof a given amount, each cable will elongate, but the cable 13 willelongate to a greater extent than the cable 14, the cable 14 willelongate to a greater extent than the cable 15, and the cable 15 willelongate to a greater extent than the cable 16. Each cable 16 isdisposed about a sheave 20 placed on each side of the runway 11 adjacentthe pendant 10. Surrounding each of cables 14, 15 and 16 loosely arefixed annuluses 21, 22 and 23. The annuluses 21, 22 and 23 areconfigured to prevent movement of the fittings 17, 18 and 19respectively therethrough, and are so placed prior to the arresting ofan aircraft that the annulus 21 is spaced along the cable 14 from thefitting 17 a distance less than the ultimate extensibility of the cable13, the annulus 22 is spaced along the cable 15 from the fitting 18 adistance less than the sum of the limits of elongation of the cables 13and 14, and the annulus 23 is spaced along the cable 16 from the fitting19 a distance less than the sum of the limits of elongation of thecables 13, 14 and 15. The annuluses 21, 22 and 23 thus serve to stop theelongation of the cables 13, 14 and 15 within the respective limits oftheir ultimate extensibility. With the respective fittings they serve assequentially operable means for controlling the relative elongation ofthe cables so that increasingly more load is required to displace thependant through four stages.

FIG. 2 shows the arresting system in operation. A relatively lightaircraft 24 has engaged the pendant 10, placing cables 13, 14, 15 and 16in tension. As explained above, all of the cables will elongate to anextent, but the cables 13, the most easily extensible cable, elongatethe greatest amount. These cables 13 have elongated until the fittings17 have contacted the annuluses 21 and some elongation of cables 14, 15and 16 has taken place before stopping the aircraft 24. Since the mosteasily extensible cables elongate to their limits first, the kineticenergy of the relatively light aircraft is absorbed gradually, and thedeceleration of the aircraft is not dangerously high.

In FIG. 3, a relatively heavy aircraft 25 has engaged the pendant,placing the cables 13, 14, 15 and 16 in tension. As pointed out above,all of the cables 13, 14, 15 and 16 elongate to some extent under anygiven tensile force, but cables 13 which are the lmost easily extensiblestretch the greatest mount. These cables 13 have elongated slowing theaircraft, until the fittings 17 have contacted the annuluses 21 (notshown) thereby ending the elongation of those cables 13. Since thecables 13 could not be elongated further, cables 14 have elongatedslowing the plane even more, until fittings 18 have contacted theannuluses 22, thereby ending the elongation of those cables 14. Sincethe cables 14 could not be elongated further, the cables 15 haveelongated slowing the aircraft even more, until the fittings 19 havecontacted the annuluses 23, thereby ending the elongation of cables 15.Since the cables 13, 14 and 15 have been stretched to their limits onlythe cables 16, the least easily extensible cables, have elongatedfurther and the plane was finally stopped.

In the embodiment shown in FIG. 4, a pendant extends across a runway 31and is adapted to be picked up by and secured to a moving aircraft.While both ends of the pedant 30 could be connected to energy absorbingmeans, such means are shown on one end only where the pendant 30 issecured to anchorage means 32 by a transmission line or cable 33.Translatable sheaves 34, 35, 36 and 37 and non-translatable sheaves 38,39, 40, 41 and 42 are placed adjacent the end of the pendant 30, andconnecting the respective translatable sheaves 34, 35, 36 and 37 to theanchorage means 32 are annealed stranded wire' extensible cables 43, 44,45 and 46, each cable being capable of a certain elongation under agiven tensile load different from that of the other extensible cables.The transmission cable 33 passes in runs alternately over thetranslatable and non-translatable sheaves so that the extensible cables43, 44, 45 and 46 are placed simultaneously in tension when load isapplied. Stops 47, 48, 49 and 50 are placed along the path of travel ofthe translatable sheaves 34, 35, 36 and 37 respectively to preventmovement of those sheaves past a certain point, and thereby to preventthe elongation of any particular cable beyond the limit of its ultimateextensibility. Each stop 47, 48,

49 and 50 is also arranged so that it will not interfere with theelongation of the other cables.

The operation of this system is quite similar to that of the FIG. 2 andFIG. 3 system. When a load is applied to the transmission cable 33 (asduring the arresting of a plane), each cable 43, 44, and 46 is subjectto a load of twice that in the transmission cable 33. Thus, when arelatively light aircraft engages the pendant 30, the most easilyextensible cables will extend the greatest amount, absorbing energygradually and insuring that the aircraft will not be decelerated toorapidly. And when a relatively heavy aircraft is to be arrested, theless easily extensible cables will come more into effect as energy isabsorbed to insure that the heavier aircraft is properly arrested.

A third embodiment of the invention is shown in FIG. 5 and here again apendant 52 extends across a runway 53 to arrest a moving aircraft. As inthe previous embodiment, the energy absorbing device could be duplicatedand disposed on either side of the runway but it is illustrated hereonly on one side. It includes a suitable abutment in the form of yoke 54from which extensible cables 55, 56 and 57 of annealed stranded wireextend in parallel arrangement to anchorage means 58. In the initialposition of the load receiving means or pendant 52 as shown in FIG. 5,there is no slack in the cable 55, there is some slack in the cable 56,and still more in the cable 57. The anchorage means 58 may be offset sothat all three cables may be of equal length and provided with slack invarying amounts, but this is not necessary.

When the load is applied to the form of the device shown in FIG. 5, thecable 55 elongates first until the slack in the cable 56 is taken up,and then they elongate together. Thereafter the cables 55 and 56elongate simultaneously until the slack in the cable 57 is taken up andall three begin to elongate together. Stop means 59 may be provided inthe path of travel of the yoke 54 to terminate the elongation of all thecables before the load receiving means extends the first-tensioned cable55 beyond its breaking point. If desired the cables 55, 56 and 57 may becapable of varying elongation under a given tensile force so that theamount of energy absorption from one stage to the next changes, but inmany instances it will suffice to have all the cables equal in thisrespect. Even when all the cables are equally extensible under a giventensile force, increasingly more load is required to move the pendantfrom one stage to the next because the retarding effect of the cables iscumulative.

In FIG. 6, stress-strain curves A, B, C and D indicate the performanceof the respective fully annealed stranded wire cables 13, 14, 15 and 16of FIGS. l, 2 and 3, for example. When those cables are arranged asdescribed and each is allowed to extend to a point within its limit ofextensibility, the stress-strain characteristics are those indicated bythe curve A, B1, C1, D1. The annealing of the cables results in anextraordinary improvement in the percentage of elongation of strandedwires of the metal cables, which results in more even deceleration ofthe arrested object and very little bounce-back.

It is thus clear that both relatively light and relatively heavyairplanes can be arrested satisfactorily by the same energy absorbingsystem, and that the kinetic energy is absorbed by a simple system ofcables.

I claim:

1. In an apparatus for absorbing kinetic energy including anchoragemeans and load receiving means displaceable from an initial positionwith respect thereto, an improved energy absorbing deviceinterconnecting the load :receiving and anchorage means comprising:

(a) two or more extensible cables each of which is fixed at one end tosaid anchorage means and connected at its other end to said loadreceiving means, said cables being arranged in parallel between saidload receiving means and anchorage means with varying amounts of slackin the respective cables when the load receiving means is in saidinitial position so 5 6 that the cables are placed in tensionsequentially References Cited drillrilng dapplication of the load anddisplacement of UNITED STATES PATENTS e oa receivmg means; (b) abutmentmeans connected to the other end of each 311911890 6/1965 Adams 244-110of said cables for movement with said cables during 5 FOREIGN PATENTStensmmg thereof; and 1,230,584 4/1960 France.

(c) xed stop means positioned in the path of move- 182 117 1/1963 Swedenment of said abutment means for terminating the elOIlgOIl 0f 2111 0fSaid CableS before the IOad IB- MILTON BUCHLER Primary Examiner. ceivingmeans extends said cables Ibeyond their breaking poinm 10 P. E.SAUBERER, Assistant Examiner.

